title: Monocarboxylate transporter-1 is required for cell death in mouse chondrocytic ATDC5 cells exposed to interleukin-1beta via late phase activation of nuclear factor kappaB and expression of phagocyte-type NADPH oxidase.
abstract: Interleukin-1β (IL-1β) induces cell death in chondrocytes in a nitric oxide (NO)- and reactive oxygen species (ROS)-dependent manner. In this study, increased production of lactate was observed in IL-1β-treated mouse chondrocytic ATDC5 cells prior to the onset of their death. IL-1β-induced cell death in ATDC5 cells was suppressed by introducing an siRNA for monocarboxylate transporter-1 (MCT-1), a lactate transporter distributed in plasma and mitochondrial inner membranes. Mct-1 knockdown also prevented IL-1β-induced expression of phagocyte-type NADPH oxidase (NOX-2), an enzyme specialized for production of ROS, whereas it did not have an effect on inducible NO synthase. Suppression of IL-1β-induced cell death by Nox-2 siRNA indicated that NOX-2 is involved in cell death. Phosphorylation and degradation of inhibitor of κBα (IκBα) from 5 to 20 min after the addition of IL-1β was not affected by Mct-1 siRNA. In addition, IκBα was slightly decreased after 12 h of incubation with IL-1β, and the decrease was prominent after 36 h, whereas activation of p65/RelA was observed from 12 to 48 h after exposure to IL-1β. These changes were not seen in Mct-1-silenced cells. Forced expression of IκBα super repressor as well as treatment with the IκB kinase inhibitor BAY 11-7082 suppressed NOX-2 expression. Furthermore, Mct-1 siRNA lowered the level of ROS generated after 15-h exposure to IL-1β, whereas a ROS scavenger, N-acetylcysteine, suppressed both late phase degradation of IκBα and Nox-2 expression. These results suggest that MCT-1 contributes to NOX-2 expression via late phase activation of NF-κB in a ROS-dependent manner in ATDC5 cells exposed to IL-1β.
authors.affiliation: Department of Biochemistry, Showa University School of Dentistry, Tokyo 142-8555, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yoshimura
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Miyamoto
authors.forename: Rika
authors.initials: R
authors.lastname: Yasuhara
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Maruyama
authors.forename: Tomohito
authors.initials: T
authors.lastname: Akiyama
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamada
authors.forename: Masamichi
authors.initials: M
authors.lastname: Takami
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Suzawa
authors.forename: Shoko
authors.initials: S
authors.lastname: Tsunawaki
authors.forename: Tetsuhiko
authors.initials: T
authors.lastname: Tachikawa
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Baba
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Kamijo
mesh_terms: D000818:Animals; D016923:Cell Death; D002460:Cell Line; D019902:Chondrocytes / Q000166:cytology*; D053583:Interleukin-1beta / Q000494:pharmacology*; D051379:Mice; D027501:Monocarboxylic Acid Transporters / Q000502:physiology*; D019255:NADPH Oxidases / Q000096:biosynthesis*; D016328:NF-kappa B / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis; D010587:Phagocytosis; D017382:Reactive Oxygen Species; D027981:Symporters / Q000502:physiology*; D000099233:Monocarboxylate Transport Protein 1
chemical_list: D053583:Interleukin-1beta; D027501:Monocarboxylic Acid Transporters; D019255:NADPH Oxidases; D016328:NF-kappa B; D052247:Nitric Oxide Synthase Type II; D017382:Reactive Oxygen Species; D027981:Symporters; D000099233:Monocarboxylate Transport Protein 1; C496317:Nos2 protein, mouse